X — index1. The orientalists who exploited lindiagns: history Eaud literature about a century ago were not always perfect in their methods of investigation and consequently promulgated many errors. Gradually, however, sounder methods have obtained and we are now able to see the facts in more correct perspective. In particular the early chronology has been largely revised and the revision in some instances has important bearings on the history of mathematics and allied subjects. According to orthodox Hindu tradition the Sz'wya Siddkdnta, the most important Indian astronomical work, was composed over two million years ago Bailly, towards the end of'the eighteenth century, considered that Indian astronomy had been founded on accurate observations made thousands of years before the Christian era. Laplace, basing his arguments on figures given by bailly considered that some years b.c. The Indian astronomers had recorded actual observations of the planets correct to one second; playfair eloquently supported bailly's views Sir william jones argued that correct observations must have been made at least as early as 1181 bc. And so on but with the researches of colebrooke, whitney, weber, thibaut, and others more correct views were introduced and it was proved that the records used by Bailly were quite modern and that the actual period of the composition of the original Sfirya Siddkiinta was not earliar than a.d. 400.